PHP PDO致命错误：调用成员函数prepare（）

Question

I am trying to display some information from database and I have the following two files. When I run the index.php , I get this error:Fatal error: Call to a member function prepare() on a non-object in C:\xampp\htdocs\pc\index.php on line 16

Could you please tell me how to solve this problem

index.php

include_once('database.php');

$db= new database();
$conn = $db->connect();
                         //Problem is in the folloing line
$query = $conn->prepare('SELECT * FROM admin WHERE admin_id = :id'); 
$query->execute(array('id' => 1));
?>
<table>
<tr>
<th>Name</th>
<th>Email</th>
</tr>

<?php
while( $rows = $query->fetch(PDO::FETCH_ASSOC)) {
    echo "<tr>";
    echo "<td>". $rows['admin_name'] ."</td>" ;
    echo "<td>". $rows['admin_email'] ."</td>" ;

    echo "</tr>";
}
?>

</table>

database.php

class Database{

private $host = 'localhost';
private $dbname = 'school';
private $username = 'root';
private $password ='';  

public $con = '';

function __construct(){

    $this->connect();   

}

function connect(){

    try{

        $this->con = new PDO("mysql:host=$this->host;dbname=$this->dbname",$this->username, $this->password);
        $this->con->setAttribute(PDO::ATTR_ERRMODE,PDO::ERRMODE_EXCEPTION);


    }catch(PDOException $e){

        echo 'We\'re sorry but there was an error while trying to connect to the database';
        file_put_contents('connection.errors.txt', $e->getMessage().PHP_EOL,FILE_APPEND);

    }
}   
}

Answer 1

class Database{

private $host = 'localhost';
private $dbname = 'school';
private $username = 'root';
private $password ='';  

public $con = '';

function __construct(){

    $this->connect();   

}

function connect(){

    try{

        $this->con = new PDO("mysql:host=$this->host;dbname=$this->dbname",$this->username, $this->password);
        $this->con->setAttribute(PDO::ATTR_ERRMODE,PDO::ERRMODE_EXCEPTION);


    }catch(PDOException $e){

        echo 'We\'re sorry but there was an error while trying to connect to the database';
        file_put_contents('connection.errors.txt', $e->getMessage().PHP_EOL,FILE_APPEND);

    }
    return $this->con; // This makes all the magic!!!
}   
}